I need to access the user’s Outlook calendar from the background service. The user may come from multiple directories or have a personal account.

Microsoft has a guide on that topic https://learn.microsoft.com/en-us/graph/auth-v2-service?tabs=http

Unfortunately, it doesn’t seem to be working with personal accounts. When I request admin consent with https://login.microsoftonline.com/common/adminconsent?client_id=my_client_id&state=12345&redirect_uri=http://localhost/

I get the following response:
AADSTS500200: User account ‘**@outlook.com’ is a personal Microsoft account. Personal Microsoft accounts are not supported for this application unless explicitly invited to an organization. Try signing out and signing back in with an organizational account.*

So, I’m wondering how to access a personal accounts’ Graph API from the background service.